Force device



Oct. 6, 1964 P. c. CLARKE 3,151,823

FORCE DEVICE Filed'Oct. 25, 1962 4 Sheets-Sheet 1 Fig,

I44 .z? Fl 2 1m 82 l 2 I6 I08 INVENTOR. PHlLlP c. CLARKE BY WWW ATTORNEYS Oct. 6, 1964 V P. c. CLARKE 3,151,823

FORCE DEVICE Filed Oct. 23, 1962 4 Sheets-Sheet 2 Fig: 4

INVE NTOR. PHILIP C. CLARKE BY m ATTORNEYS Oct. 6, 1964 p, c, CLARKE 3,151,823

FORCE DEVICE Filed Oct. 23, 1962 4 Sheets-Sheet 3 INVENTOR. P HlLlP C. CLARKE Q 094 ATTORNEYS Oct. 6, 1964 P. c. CLARKE 3,151,823

FORCE DEVICE Filed on. 23, 1962 4 Sheets-Sheet 4 Fig. F '9. /2

322 8 g \I 1h \Y] 2 /2 4 \IO 8 l t 31 G 296 E 308 I80 3K) 305 INVENTOR. so 305 PHILIP c. CLARKE 29s BY 3|4 3 2 ATTORNEY United States Patent EAL-33,823

Patented st. 6, 1964 i a showing the details of construction of the weight emr151r323 ployed in the device of FIGURE 10;

FORCE DEVIIIE Philip C. Ciarlre, Lansdale, Pa, assignor to Ametelr, Inc, New York, N.Y., a corporation of Delaware Filed Oct. 23, 1962, Ser. No. 232,368 9 Claims. (Cl. 242-1975) This invention relates to a cable force device. The device of this invention has particularly valuable application to tensioning, for example, orthopedic tensioning in connection with which the invention will be described for purposes of illustration.

For orthopedic tensioning and other force applications as well, the device of this invention is advantageous in providing tension varying means md means to indicate the tension. Further, it greatly facilitates set-up as contrasted, for example, with the customarily used weights. Since there is no inertia as is the case with traction weights, the orthopedic patient does not experience pain due to sudden changes in position. Further, more freedom of motion is possible since the variation in tension is negligible over the distance the patient generally moves.

Additional advantages are the reduction of likelihood of unauthorized changes in load to relieve the patient and freedom from the complexity of weights, pulleys and lines involved in the usual set-up which hinder the handling of the partient and are a hazard to visitors and staff members.

This invention is a marked improvement over the force device disclosed in my co-pending application, Serial No. 209,455, filed on July 12, 1962. The device of this invention markedly facilitates set-ups by readily providing a reduced tension during set-up for the cable which is employed to exert tension. The device is further markedly advantageous in that it is highly accurate having means to compensate for the force exerted by the device itself. In addition, the device of this invention is provided with novel means to control the rewind speed of the force device.

The invention and its objects will be understood from a reading of the following description in conjunction with the drawings in which:

FIGURE 1 is a front elevation, partially broken away, of a force device in accordance with this invention;

FIGURE 2 is a vertical section through the force device of FIGURE 1 taken on the planes indicated by the lines 2-2 in FIGURE 4;

FIGURE 3 is an enlarged horizontal section of the governor of the force device of FIGURE 2 taken on the plane indicated by the line 33 in FIGURE 2;

FIGURE 4 is a section of the force device of FIGURE 1 taken on the planes indicated by the line 44 in FIG- URE 2;

FIGURE 5 is a fragmentary view showing the worm and worm gear of FIGURE 4 in the disengaged position;

FIGURE 6 is a side view of the pulley employed in the force device and shown in FIGURE 4;

FIGURE 7 is a vertical section partially broken away of a force device similar to the force device of FIGURES 1-5 showing an alternative worm and worm gear arrangment, an alternative motor for set-up and a fail-safe device;

FIGURE 8 is a plan view partially broken away taken on the plane indicated by the line 3-% in FIGURE '7;

FIGURE 9 is a horizontal section taken on the plane indicated by the line 2 9 in FIGURE 7;

FIGURE 10 is a horizontal section through a force device similar to the force device of FIGURE 1 having an alternative device for compensating for the force exerted by the device of the invention;

FIGURE 11 is a side elevation partially broken away FIGURE 12 is a section taken on the plane indicated by the line 12-12 in FIGURE 11; and

FIGURE 13 is a perspective view of the weight compensating mechanism of the force device shown in FIG- URES 2 and 4.

Referring now particularly to FIGURES 1, 2 and 4, a force device 2 has casing members 4 and 6 enclosing a frame 8 comprised of frame members It and 12 which are secured together, for example, by welding.

A hollow reel 14 is mounted for free rotation about bushing 18 fixedly secured to shaft 16, which is journalled to frame member 10. Bushing 18 is freely rotatable in a U-shaped cup member 20. A power spring 22 has one end secured by a rivet 24 to member which is fixedly secured to frame 12. The outer end of spring 22 is secured to an inverted cup-shaped freely rotatable spring housing member 26 as by a rivet indicated at 28. Member 26 is fixedly secured to reel 14 for rotation therewith. Fixed plate 30 completes the spring housing.

A main power spring 34 (FIGURE 4) has its inner end secured at 36 to bushing 18 and has its outer end secured as by rivet 443 to the inner periphery of reel 14.

A cable 44, preferably a wire cable covered with a low friction coating material such as nylon, is wound on reel 14- and passes over pulley 46 and through a guide grommet 48. Cable 44 is provided with a securing eye 50 at its outer end (FIGURE 2). Pulley 46 is mounted for free rotational and axial movement on shaft 52 which is mounted in an opening 54 in frame member 12 (FIG- URE 6), and passes through an opening 56 in frame member 10, shaft 52 being held in position by snap rings 58 on opposite sides of frame member 10.

Shaft 16 is fixedly secured to hub 64 of worm gear 66 (FIGURE 2) which in turn is engaged by a worm 68 which is splined to a shaft 70. Shaft 70 is mounted for rotation in struck-up brackets 72 and 74 being held from longitudinal movement by virtue of snap rings 76 and an enlarged head 78 which contains a hexagonal bore 80 adapted to receive hexagonal end 82 of crank 83 (FIGURE 1). A finger 84 (FIGURES 4 and 5) which is adapted to engage worm 68 before it disengages from worm gear 66 is pivotally mounted on a fixed pin 86 and is biased to the position shown in FIGURE 4 by the two arms of a torsion spring 88 which have downwardly extending portions which lie on either side of abutment 89.

The force device 2 is provided with speed governing means. Side 96 of reel 14 (FIGURE 2) is in the form of a gear which engages pinion 98 fixedly secured to rotatably mounted shaft 100. Shaft 100 is fixedly secured to gear 102 which in turn drives pinion 104 fixedly secured to a shaft 106. Shaft 1116 is mounted for rotation in frame 10 and in governor housing 108, the shaft being held from axial movement by means of split rings and 112.

A split friction member 116 (FIGURES 2 and 3) is adapted to engage the inner cylindrical wall 118 of governor housing 108 and comprises a pair of semi-circular portions 120 and 122. Each of portions 120 and 122 has a circumferential groove 124 which accommodates a garter spring 126 which tends to bias portions 120 and 122 towards each other. Shaft 106 has a squared portion 130 which engages conforming grooves 132, 132 in portions 120 and 122. A washer 134 and a collar 136 afiixed to shaft 106 is provided on either side of friction member 116 to prevent its axial movement.

The force device 2 is secured to a fixed support member (not shown) by means of bar 142 (FIGURES 1 and 4) which is provided with openings 144 for the reception of, for example, securing straps indicated at 146 in FIG- URE 1. Bar 142 passes through an opening 147 in casing member 4 and is pivotally connected to a pin 148 (FIGURE 13) secured between lever 156a and lever Gb tied together by a pin 159a. Lever 159a and lever 15% are pivotally mounted on pin 152 welded to frame member 12 and having a reduced portion 152a accommodating lever 1561i and against which lever 15% which is pivoted on a further reduced portion 1152b is held by a split ring 1526 (FIGURE 13). Pin 1500 is engaged by one end of extension spring 156 which has its other end secured to bracket 158. Spring 156 is the main weighing spring of the force device 2.

The thus described main weighing system is connected to a force indicator through a spring-weight compensating system as best seen in FIGURE 13. A U-shaped extension 162 of lever 15% acts as a support for one end of each of a pair of compression coil springs 164 and 166 Whose opposite ends abut finger 163 which is an integral part of lever 176. Lever 171i is pivotally mounted at one end on reduced portion 152e of pin 152 and is held against the larger portion 15212 by a split ring 152d. A weight 173 has a slot 174 receiving lever 170 to which it is held adjustably by a set screw 176. Pivoted lever 171 is pivotally connected at 178 to a lever 18!) which is operatively connected to a force indicating mechanism 182 (FIGURE 2). Force indicator 182 is a conventional one of the pointer-dial type and hence need not be described in detail here. Lever 181) (FIGURE 2) is connected pivotally as indicated at 184 to a pivoted sector gear 186 which in turn engages a pinion 188 fixedly secured to shaft 190 which actuates pointer 192 over a dial 194.

Operation In the preferred manner of operating the force device 2, crank 83 will be rotated counterclockwise to back worm 68 off from worm gear 66 which is accomplished by advancing Worm 68 towards finger 84 until the worm is engaged by finger 84 which will result in the continued retraction of worm 68 away from form gear 66. Torsion spring 88 will keep finger 84 centered up during the retraction of Worm 6S and until worm 68' is stopped by engagement with bracket 74. At this stage the continued turning of worm 68 will cause finger 84 to hip over a land into an adjacent groove for each complete rotation of the worm thus causing a repeated clicking which will notify the operator that the worm is fully disengaged from the worm gear and that hence the main power spring 34 is effectively out of action since shaft 16 is now free to rotate as rotation of reel 14 moves power spring 34.

Extension of cable 44 to the desired point of attachment, for example, to a remote orthopedic sling can now readily be carried out. As cable 44 is extended with the consequent rotation of reel 14, the main power spring 34 will not exert force since shaft 16 is no longer restrained by the interaction of worm gear 66 and worm 68. The rotation of reel 14 will result in the rotation of spring housing 26 and the consequent winding up and exertion of force by power spring 22. However, the selection of power spring 22 to exert only a relatively small tension for the winding up of cable 44 on reel 14 makes it a very simple matter to handle cable 44 during the set-up procedure. This is in marked contrast to the more complex set-up where the powerful main power spring 34 is wound up on the extension of cable 44 as would be the case if worm wheel 66 and worm 68 were always in engagement. This latter situation either results in the exerting of a very large tension which makes it diificult to manage cable 44 or alternatively means that the worm must be turned during the extension of cable 44 to 'reduce the tension exerted by the main power spring 34. It will be appreciated that the arrangement of this invention markedly simplifies the handling of the set-up of the force device.

After the set-up has been accomplished with the cable 44 secured to the desired remote point, crank 82 is employed to rotate shaft 70 to cause worm 68 due to its 4 engagement with finger 84 to advance towards and engage worm gear 66 until worm 68 abuts against bracket 72. Now by continued cranking of shaft 76) clockwise, worm 68 and worm gear 66 cause shaft 16 to rotate clockwise as viewed in FIGURE 4 and wind up power spring 34 to exert the desired tension on cable 44, as indicated by pointer 192 on dial 194.

In many forms of application, such as for example, orthopedic work, it is necessary that the indicated force be accurate. It is evident that an inaccuracy in the indicated force will be caused by the weight of the force device 2 when it is hanging vertically due to the substantial weight of the force device itself. Indeed, a substantial error in indicated force will be occasioned except when the force device is relatively close to the horizontal, i.e. with the tensioning cable and the securing bar substantially horizontal. The force device of this invention accurately compensates for such error.

As previously indicated, the force exerted is measured by the displacement of weighing spring 156 incident to the pivoting of levers 156a and 15Gb. Absent any compensation device, the force indicated by pointer 192 over dial 194 would over-indicate the force exerted by the device by an amount equal to the weight of the device when it is hanging straight down from a support. Similarly, if the device were secured in an inverted manner resting on bar 142, a result in the opposite direction would be incurred if no compensating device were present. It will be noted, however, that the movement of levers a and 15612 is not directly carried to the force indicator mechanism 182 but rather the force is transmitted through extension 162 and springs 164 and 166 to lever 170 which carries weight 173 and which is directly linked to the force indicator mechanism 182 by lever 13).

Weight 173 is distanced from pin 152 and the force of compression springs 164 and 166 are selected so that,

when the force device 2 is mounted vertically as discussed above, movement of lever 170 will cause pointer 192 to move over dial 194 an amount equal to the indicated weight of the force mechanism 2. Thus, when thedevice is mounted with the cable 44 running straight down, this compensating system will cause the pointer 192 to move clockwise as viewed in FIGURE 1 and subtract the weight of the force device. Similarly, in the reverse position with the bar 142 resting on a support, the pointer 192 will be moved counterclockwise so as to indicate the additional force exerted by the weight of the force mechanism. By the same token, correction for the intermediate positions in which the force device 2 is placed other than the hori- Zontal position will be made. In order to insure the best accuracy of compensation, force device 2 should be mounted so that the cable 44 in eflfect runs in a straight line away from the force device.

An alternative reeling mechanism which can be employed in the force device of this invention is shown in 7 FIGURES 7 through 9. A reel 204 on which cable 44 is wound ismounted for free rotation on a shaft 206 which is rotatably mounted in frame members 10 and 12 'and to which is fixedly secured a spacing collar 208.

Reel 2114 is hollow and contains a power spring 210 (FIGURE 9) secured to its periphery by a rivet indicated at 212 and having its inner end secured at 214 to a bushing 216 fixedly secured to shaft 296.

Flange 225) of reel 264 is fixedly secured as by welding to flange 222 of a drum 224 which is mounted for free rotation on shaft 266 and is spaced from frame 12 by a washer 225. Adjacent drum 224 is a storage drum 226 mounted for free rotation on shaft 228. A tightly coiled non-cumulative force spiral spring 230, for example, of the type disclosed in Patent No. 2,609,191 or 2,609,192 is wound on drum 226 with its extended portion reverse wound on drum 224 as best seen in FIG- URE 7 to form what is known as a B motor which is disclosed in Fornelius Patent No. 1,977,546.

Shaft 296 is fixedly secured tohub 236 of worm gear 238 which engages worm 240. Worm 240 is splined on shaft 242 which is mounted for rotation in brackets 243 and 244 and is held from axial movement by virtue of its enlarged head 245 which is adapted to receive crank 83 and spring clip 246.

A slide 247 is slidably mounted in bracket 24% and is biased to the right as viewed in FIGURE 7 by an extension coil spring 256 against a stop member indicated at 251. Slide 247 has an upstanding member 252 provided with a finger 254 adapted to engage threads of worm 240.

In lieu of the governor of the first described embodiment, the reeling in of cable 44 at an excessive speed can be prevented by a centrifugal force stop mechanism 262 which is best seen in FIGURES 7 and 9. Stop mechanism 262 is provided with a pawl 264 which is pivotally secured to reel 204 by means of a headed pin 266. A bowed leaf spring 268 has one end secured to pin 270 which is fixedly secured to reel 284 and has its other end secured to pawl 2&4 as indicated at 272. Pawl 64 has a tooth portion 274 which is adapted to engage a stop 276 when reel 2G4 turns at a sufficient speed to cause centrifugal force to pivot pawl 264 counterclockwise as viewed in FIGURE 9 against the force of spring 268.

Operation The operation of this alternative embodiment of the invention is essentially the same as the operation of the first described embodiment. In order to set-up, power spring 219 is taken out of action by backing off worm 240 from worm gear 238 by the rotation of shaft 242. As worm 240 backs off from worm gear 238, it is engaged by follower 254 of slide 247 which permits the worm 246 to be backed off until it abuts against bracket 244 to completely disengage it from worm gear 238. At this point as the shaft 2 42 continues to be rotated, follower 254 is forced to move over a land into the adjacent groove for each complete rotation of worm 24%) causing a clicking sound to advice the operator of the full disengagement of the worm from the worm gear.

Cable 44 can now be unreeled from reel 264 to the desired point of connection without winding main power spring 210. The unreeling will cause the counterclockwise rotation of drum 224 as viewed from the top of the device causing non-cumulative force spring 231) to be wound onto this drum in the manner of a conventional B motor. The force exerted by the B motor will be of the order necessary to reel in cable 44 and insuflicient to in any way hinder the operation of cable 44 during set-up. Since the B motor will exert a relatively constant force, a build up of force as the cable 4 5 is extended is avoided.

When the cable 44 is secured and it is desired to exert substantial tension on it, shaft 242 will be rotated to advance worm 240 back into engagement with worm gear 233 and abutting against bracket 243. The continued rotation of shaft 242 will result in the rotation of shaft 296 and the consequent winding up of main power spring 21 9 until the desired tension via cable 44- is being exerted.

Should cable 44 become unsecured or otherwise is inadvertently permitted to rewind when it is exerting a substantial tension due to the force of spring 210, the centrifugal force exerted by the rapid turning of reel 294 will cause pawl 264 to move outwardly and engage stop 276 to prevent further reeling of cable l and possible damage due to the excessive speed of reeling in.

An alternative weighing and compensating structure which can be substituted for the weighing and compensating structure in force device 2 is shown in FIGURES 10 through 12. Here the lever 18-9 which is connected to the force indicating mechanism shown in the force device 2 (FIGURE 2) is pivotally connected at 292 to a bracket 294 secured to a hollow cylindrical weight 296. Bearing springs 298 and 3% formed of thin spring steel and having spiral cut out portions 362 and 364, respectively, have their outer peripheries secured to opposite ends of weight 296 by means of screws indicated at 395. A rod 366 has a reduced threaded portion 308 passing through central opening 310 of spring 29% and has secured thereon a washer 312 and a nut 314 to secure the central portions of spring 2% to rod 3%. Rod 3% passes through central opening 315 of spring 3% which is secured to rod 3% by virtue of being between enlarged portion 32% of rod 3-95 and recessed spring clip 318. Rod 3% has a bifurcated end 322 which is fixedly secured to securing bar 32 which is provided with openings 326 by means of which it can be secured to a support.

A rod 33% is fixedly secured to bar 324 and has a threaded portion 332 to which a collar 334 is threadedly secured. Rod 3343 passes freely tnrough a collar 33-5 secured in opening 338 in spring housing 346) which is fixedly secured to frame member 12. Rod 33% has a reduced end portion 344 which passes through a collar 346 mounted in opening 348 in spring housing 349. A compression coil spring 350 is interposed between spring housing 349 and collar 334 and a second compression coil spring 352 is interposed between the opposite side of collar 334 and the opposite end of spring housing 340.

Operation The operation of the immediately above described weighing and compensating structure is similar to the above described structure. The main weighing spring is compression spring 35%) which is preloaded by spring 352, to a point where the gradient of spring 359 is substantially linear. As the force device exerts its force, bar 324 moves relative to the frame 8 of the force device and car ries with it rod 3%, weight 296, bracket 294. Assuming the force device to be horizontal, the weight 296 will not deflect springs 29% and 3% and the full deflection of spring 359 will be transmitted to lever 13% of the force indicating device to give a true indication of the force being exerted by cable 44. If the force device is hanging downwardly, a portion of the force causing relative movement between bar 325 and frame 8 is the weight of the force device itself and hence the force being exerted by cable 44 is less than indicated force unless this factor is compensated for. In this instance the compensation is taken care of by the selection of the weight 296 and the stiffness of springs 298 and 3%. It will be seen that with the force device disposed in this position, weight 2% will move downwardly relative to rod 3% an amount to subtract the weight of the force device being exerted against spring 359 from the indicated force. Similarly, when the device is disposed in the inverse position and supported on bar 324, the weight will move in the opposite direction with respect to rod 3% in order to provide for a movement of the force indicator to add the weight of the force device and correctly show the force being exerted by cable 44.

It is to be understood that the above specifically described embodiments of the invention are by way of illustration only and are not intended to be limiting.

What is claimed is:

l. A force device comprising a reel, means mounting said reel for rotation, a line coiled on the reel, a main spring motor connected to the reel, means disengageably connected to the main spring motor to vary the force bein exerted by the main spring motor and deactivate the spring motor independent of the winding relationship of the line and the reel and an auxiliary spring motor connected to said reel to provide a rewinding force when the main spring motor is deactivated.

2. A force device in accordance with claim 1 in which the disengageable means comprises a worm gear connected to the main spring motor and a worm disengageable from the worm gear.

3. A force device in accordance with claim 1 in which the disengageable means comprises a worm gear connected to the main spring motor and a worm disengageable from the worm gear, a shaft for rotating the worm, the

Worm being splined to the shaft, a stop to prevent the worm from advancing out of engagement with the worm gear in one direction and finger means for engaging the worm to permit it to back ofi clear of the worm gear in the other direction.

4. A force device in accordance with claim 1 in which the disengageable means comprises a worm gear connected to the main spring motor and a worm disengageable from the worm gear, a shaft for rotating the worm, the worm being splined to the shaft, a stop to prevent the worm from advancing out of engagement with the worm gear in one direction, finger means for engaging the worm to permit it to back off clear of the worm gear in the other direction and a stop to limit the distance the worm is backed clear of the worm gear, said finger means being spring biased to a position for engagement of the worm whereby the finger means on rotation of the worm in contact with the second-mentioned stop will move over an adjacent land of the worm and into the adjacent groove to produce a sound indicating that the worm is free of the worm gear.

5. A force device in accordance with claim 4 in which the finger means includes a slide.

6. A force device in accordance with claim 4 in which the finger means comprises a pivoted finger.

7. A force device comprising a reel, means mounting said reel for rotation, a line coiled on the reel, spring motor means connected to said reel, means independent of said line to vary the force exerted by said spring motor, a weighing spring having one end secured to the force device and one end secured to means for securing the l 8 V V force device, means connecting the securing means to the force indicator, said connecting means including a force compensation device comprising a weighted member mounted for movement in the direction of movement of the weighing spring and spring means to bias the weighted member against movement.

8. A force device in accordance with claim 7 in which the weighted member is a weighted pivoted lever.

9. A force device comprising a reel, means mounting said reel for rotation, a line coiled on the reel, spring motor means connected to said reel, means independent of said line to vary the force exerted by said spring motor, a weighing spring having one end secured to the force device and one end secured to means for securing the force device, means connecting the securing means to the force indicator, said connecting means including a force compensation device comprising a hollow weight, a plurality of flat bearing springs secured to the weight, a rod connected to the bearing springs, the said rod being connected to the securing means and the said Weight being connected to the force indicator.

References Cited in the file of this patent UNITED STATES PATENTS 1,119,887 Shanahan Dec. 8, 1914 1,500,938 Howard July 8, 1924 1,926,452 Norling Sept. 12, 1933 2,293,755 Joabson Aug. 25, 1942 2,945,921 Belicka et a1. July 19, 1960 2,997,250 Collins Aug. 22, 1961 3,085,768 Treutelaar Apr. 16, 1963 

1. A FORCE DEVICE COMPRISING A REEL, MEANS MOUNTING SAID REEL FOR ROTATION, A LINE COILED ON THE REEL, A MAIN SPRING MOTOR CONNECTED TO THE REEL, MEANS DISENGAGEABLY CONNECTED TO THE MAIN SPRING MOTOR TO VARY THE FORCE BEING EXERTED BY THE MAIN SPRING MOTOR AND DEACTIVATE THE SPRING MOTOR INDEPENDENT OF THE WINDING RELATIONSHIP OF THE LINE AND THE REEL AND AN AUXILIARY SPRING MOTOR CONNECTED TO SAID REEL TO PROVIDE A REWINDING FORCE WHEN THE MAIN SPRING MOTOR IS DEACTIVATED. 